The invention relates to improvements for testing multiple engines on testing stands.
More particularly, the invention relates to engines to be tested which are cooled by a liquid coolant or by air coolant that are lubricated with an arrangement for warming the internal combustion engines on the testing stand in an improved manner prior to a test load being applied.
The invention finds particular use in production testing stands on which newly manufactured internal combustion engines are broken in, tested, and set after being fully assembled. When no faults that must be corrected are diagnosed, and the engine approved, the dwell time of the individual internal combustion engine at the testing stand must be kept extremely short so that the testing costs remain low. Short residence times without sacrifices in testing quality are only possible when all operations to be implemented at the testing stand and particularly the break-in time are time minimized.
A shorter break-in time on such testing stands is only possible without the qualitative deterioration of the results is possible only when the respective internal combustion engine parts such as pistons, bushings and plain bearing location and parts that are subjected to friction are at satisfactory operation temperature.
What is referred to as the break-in period is divided into two stages. In the first stage, the operator waits for the warm-up of the engine according to the current state of the art by allowing the internal combustion engine to run at higher speed and without load. Thereupon the power of the internal combustion engine is gradually increased to maximum power and is held thereat at the second stage on the basis of testing various specific situations of speed and load. Since the gradient of the warm-up, the internal combustion engine is dependent both on the internal power loss as well as the externally supplied heat on the motor mass, internal combustion engines having fewer cylinders and a lower nominal speed are great disadvantages in the warm-up in comparison to engines having more cylinders and higher nominal speeds. In particular, internal combustion engines running at lower nominal speeds in comparison to the maximum speed allowed often force the operator to accept a warm-up phase on the order to 15 through 25 minutes in the methods heretofore used and this drives the testing cost significantly higher.
It is accordingly an object of the present invention to avoid the disadvantages of the two stage testing operation and to obtain a shortening of the warm-up of the parts of the internal combustion engine to attain operating temperature.
A further object of the invention is to provide an overall improved testing method and apparatus for testing which shortens the time on the test stand and which has no negative influence on the quality of the testing or on the functioning of the parts of the tested internal combustion engine.
A still further object of the invention is to provide an improved means of rapidly conditioning an engine on a test stand to place it in condition for testing and to do this with the conservation of heat energy generated in the coolant and lubricant during the testing period.